Browse Prior Art Database

Variable Gain Diffusing Optical Projection Screens

IP.com Disclosure Number: IPCOM000043996D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Feigenblatt, RI: AUTHOR

Abstract

A method is provided whereby the diffusing action of a transmissive screen of fixed geometry is made controllably and continuously variable with a homogeneous liquid mixture. A hollow acrylic screen of fixed geometry contains a diffusing interior surface 11 and is filled with a miscible mixture of liquids 12 of different refractive indices. By varying the proportion of the components, the index of the mixture is continuously varied as is the refractive mismatch at the diffusing surface boundary. By keeping the liquid layer thin a small amount of liquid is necessary. As a continuous range of screen gains is achieved by varying the refractive index of the filling liquid, only a single mold is required for the acrylic diffuser. The screen gain can be set at the factory, or reset in the field, by refilling the screen.

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Variable Gain Diffusing Optical Projection Screens

A method is provided whereby the diffusing action of a transmissive screen of fixed geometry is made controllably and continuously variable with a homogeneous liquid mixture. A hollow acrylic screen of fixed geometry contains a diffusing interior surface 11 and is filled with a miscible mixture of liquids 12 of different refractive indices. By varying the proportion of the components, the index of the mixture is continuously varied as is the refractive mismatch at the diffusing surface boundary. By keeping the liquid layer thin a small amount of liquid is necessary. As a continuous range of screen gains is achieved by varying the refractive index of the filling liquid, only a single mold is required for the acrylic diffuser. The screen gain can be set at the factory, or reset in the field, by refilling the screen. Variable diffusing might, instantaneously, be achieved by using a very compressible liquid and a pump, or precisely controlling the critical opalescence of a liquid in an unstructured container.

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